Cuap. X. CONDUCTING TISSUES. 247 
more central ones. The properly directed movement 
of the tentacles is not an unique case in the vegetable 
kingdom, for the tendrils of many plants curve to- 
wards the side which is touched; but the case of 
Drosera is far more interesting, as here the tentacles 
are not directly excited, but receive an impulse from 
a distant point; nevertheless, they bend accurately 
towards this point. 
On the Nature of the Tissues through which the Motor 
Impulse is Transmitied—It will be necessary first 
to describe briefly the 
course of the main fibro- 
vascular bundles. These 
are shown in the accom- 
panying sketch (fig. 11) 
of a small leaf. Little 
vessels from the neigh- 
bouring bundles enter 
all the many tentacles 
with which the surface 
is studded; but these 
are not here represented. 
The central trunk, which 
runs up the footstalk, 
bifurcates near the centre 
of the leaf, each branch Fre. 
bifurcating again and (Drosera rotundijolia.) 
a a Diagram showing the distribution of the 
again according to the vascular tissue in a small leaf. 
size of the leaf. This 
central trunk sends off, low down on each side, a 
delicate branch, which may be called the sublateral 
branch. There is also, on each side, a main lateral 
branch or bundle, which bifurcates in the same 
manner as the others. Bifurcation does not imply 
that any single vessel divides, but that a bundle 
17 
